A lxGa1- xN and GaN/A lxGa1- xN quantum wells were successfully grown on basal plane sapphire substrates by gas source molecular beam epitaxy using ammonia as nitrogen source. Photoluminescence measurements were carried out for the samples grown. The results show that the blue shifts in optical transition energy due to quantum size effect are 57meV at room temperature and 49meV at 80K for the GaN/Al0.12Ga0.88N quantum well sample having 6 GaN wells each with width of 7nm.
The design and fabrication of 1.55um wavelength Multiple Quantum Well (MQW) Distributed Feedback (DFB) laser integrated with electroabsorption modulator is reported. A static single longitudinal mode output power greater than 6mW in free space is obtained, with 0V bias to the 150um length modulator and an extinction ratio of up to 11dB at 4V at 100mA operation current of 300um length DFB laser. The modulator side and DFB laser side are coated with Antireflcetion (AR) and High reflection (HR) coating respectively. The threshold current of DFB laser is about 16mA and the side mode suppression ratio is always greater than 35dB when the reverse bias voltage of the modulator is varied from 0V to 4V.